Pilot Bushing - Joe/Duke/et al

[Dennis C.]

This issue may have been beat to death already - however, your opinion please.
I had a series of bad luck stories using "bronze" (NAPA) pilot bushings. After a few hundred miles, would sound like the clutch, throwout bearing and the transmission were going to drop on the ground. When I went to R&R, I.D of bushing was way bigger than it should be. Switched to GM needle bearing item and have had no problem since. I have to assume bronze item works - but - what am I missing???

[Duke W.]

Re: Pilot Bushing - Joe/Duke/et al

I only replaced the bushing in my Corvette once when I rebuilt the engine. I don't think the original was in bad shape at 115K miles, but it was a good time to just do it. Bought the bushing from GMPD. The clutch and bushing in my Cosworth Vega are still original at 75K miles.

One issue might be lubrication. I recall that the bushing is oil impregnated sintered bronze, and the shop manuals caution not to lubricate it, but I think a lot of guys put grease on it, which is probably not a good idea.

Duke

[Mike M.]

Re: Pilot Bushing - Joe/Duke/et al

dipstick. I've never had problems with oe bronze bushings beginning in l961 when i installed a bronze bushing in a 394 olds engine. I agree with duke that the bronze bushings are self lubricating, but i always used a LITTLE Never Seize when installing the clutch assembly. However, in last 10 years or so I've switched to the caged needle bearings, not because of any personal failure experiences with bronze, just makes sense that a bearing is superior to a bushing but i'm no engineer, or spelling whiz for that matter.Bogus mikie

[Ed Jennings]

Re: Pilot Bushing - Joe/Duke/et al

If the bronze bushing kept wearing rapidly it could be a sign of a bent inputshaft or bad input shaft bearings. Something has been putting an unusual load on the bushing.

[Tom H.]

Re: Pilot Bushing - Joe/Duke/et al

I think the DO NOT LUBE caution was to prevent some ham fist from loading the cavity with grease which could spin out all over the clutch facing with obvious consequences. I've lightly lubed the bearing with high temp grease for years with no adverse effects. I emphasize lightly!!!!!!!!!!!!!!!

[Mike M.]

Re: Pilot Bushing - Joe/Duke/et al

agree with ed. another possibility is misalignment of tranny to bellhousing. have seen this before on Fords. mike

[John H.]

Re: Pilot Bushing - Joe/Duke/et al

I've used the GM needle bearing on many installations over the years with no problems (same bearing-better-than-a-bushing logic); GM designed the needle bearing for the 6.2L truck diesel, as diesel truck owners don't appreciate having to do a teardown just to replace a $6.00 Oilite bushing. I always do a concentricity check on the bellhousing opening vs. the flywheel with a dial indicator before installing the engine - have never found one out of spec with a stock bellhousing, but every time I've used a Lakewood or McLeod, I've had to use Tavia offset dowels to bring them into spec. For $7.00 more than the Oilite bronze bushing, the needle bearing seems like a good long-term investment.

[Dennis C.]

Re: Pilot Bushing - Joe/Duke/et al

Thanks guys... Survey seems to me to say - go ahead and pay the extra frogskins for the GM needle bearing item. That what I be do'in... No matter how many times I have changed one, its never been all that much fun.

[Craig S.]

Re: Pilot Bushing - Joe/Duke/et al

Does anyone have the P/N handy? I am about to order parts for my 66 L72....thx!....Craig

[Joe L.]

Re: Pilot Bushing - Joe/Duke/et al

Dennis-----

The bronze pilot bushing has changed part numbers over the years. I have heard of problems like the one of which you speak with the bushing which GM currently offers under GM #10125896. It is highly possible that GM's source for this bushing is the same as NAPA's.

An oil-lite bronze bushing requires only a few drops of machine oil to lubricate. The sintered bronze material will only absorb oil. Grease is a combination of an oil + a soap. If grease is applied, only the oil fraction will be absorbed and the soap will be left behind to, possibly, cause problems. It certainly won't do any good.

It is also possible, of course, that your problem like yours could be caused by a bent or mis-aligned transmission input shaft. However, I consider that HIGHLY unlikely in your case. The needle bearing-type pilot bearing is FAR more sensitive to such mis-alignment than the bronze bushing. In fact, that's the ONLY down-side to using the needle-bearing unit; you must be sure that your bellhousing-to-block alignment is within spec. So, if your problem with the bronze bushing was due to misalignment, you would have had even more problems with the needle bearing unit. The needle bearing unit will not wear-in to correct VERY SLIGHT misalignment as the bronze bushing will.

The needle bearing unit is available from GM as well as aftermarket sources. From GM, it's GM #14061685 and GM lists for $13.56

[Mike M.]

Re: Pilot Bushing - Joe/Duke/et al

have fun next time you remove the bronze bushing. Pack the end of the crankshaft(in front of the bushing with the thickest grease you can find(Your lipstick might do), then drive in a cut off end of a trashed input shaft. they usually pop right out. otherwise, its chisel time. mike

[Clem Z.]

to remove the bronze bushing just

thread in a 5/8" tap and as the tap bottoms out on the crankshaft it will push the bushing out as you keep turning the tap. no muss no fuss

[Mike M.]

Re: to remove the bronze bushing just

Clem, neat idea. thanks, mike

[Clem Z.]

Re: to remove the bronze bushing just

every engine i build and rebuilt over the last 40 years i changed the bushing that way,it is a lot less messy than the grease deal and you will not hit your thumb with a hammer.

[Ed Jennings]

Re: to remove the bronze bushing just

Great idea. Now, if I can just remember this trick the next time I have to take a bushing out.................